Massive explosions. Lava fountains. Mushroom clouds. Pyroclastic flows. Lahar. We’re familiar with these natural occurrences that result from volcanic eruptions.
But not many of us know about a different, much weirder type of eruption. It’s called limnic eruption. It’s so rare and bizarre that there are only two recorded eruptions of this kind in history: at Lake Monoun in 1884 and Lake Nyos in 1986.
What is a limnic eruption?
A limnic eruption, also known as lake overturn, is a type of natural disaster that occurs when a large amount of carbon dioxide erupts from the bottom of a deep lake. It explodes upward when it reaches the top, and then goes down the slopes, suffocating humans, livestock, wildlife, and just about everything in it’s path.
There’s no fire, smoke, ash, and lava – just tremendous amount of carbon dioxide getting discharged all at once. In their investigations of the limnic eruptions at Lake Monoun and Lake Nyos, both located in Cameroon, scientists have determined that, although indirectly related, volcanic eruptions and limnic eruptions are separate types of events.
What causes limnic eruptions?
A limnic eruption can occur if the lake is almost saturated with carbon dioxide, produced largely by a volcano under the lake or from decomposing organic material. Take a carbonated beverage as an analogy of how limnic eruptions work.
The lake behaves like an unopened can of soft drink before it is saturated. In this state, the carbon dioxide is dissolved in the water. However, opening the can releases pressure and the gas comes out of the solution, forming bubbles.
Carbon dioxide saturation makes the lake at a very critical and unstable point. It only needs a trigger to set off a massive eruption. Triggers can be landslides, earthquake, volcanic eruption, or an explosion. Limnic eruptions can also be triggered by rain storms or even strong wind.
What happened at Lake Monoun and Lake Nyos?
The limnic eruption at Lake Monoun asphyxiated and killed 37 people living in the vicinity. A tsunami around 31 feet was believed to be pushed out from the lake, flattening vegetation 100 meters around Monoun’s eastern end.
People near the 3-meter high gas cloud reported smelling the gas as acidic and bitter. This indicates that a dissolved acid may have been mixed with carbon dioxide. The gas cloud dissipated after 4 hours to dissipate.
The event at Lake Nyos was much catastrophic and deadlier, releasing more than 80 million cubic meters of carbon dioxide. The eruption killed more than 1,700 lives by asphyxiation, with much loss of wildlife and livestock.
Can limnic eruptions be prevented?
Yes, there have been efforts at developing a solution to extract massive amount of gas from lakes to avert a build-up that could result in another disaster. Scientists have been using siphons to degas Lake Monoun and Lake Nyos in a controlled manner.